A Vertical Axis Wind Turbine (VAWT) of any significant size, whether used on land or substantially stationary barge or platform locations, typically needs bearings adjacent the top and bottom thereof in order to mount the substantially vertical shaft of the VAWT securely for proper rotation. This typically requires building some sort of rigid supporting structure of significant size, such as the three legged tower shown in U.S. Ser. No. 11/265,278 filed Nov. 3, 2005, the disclosure of which is hereby incorporated by reference herein, or the very heavy single supporting central pedestal, such as shown in U.S. Pat. No. 4,359,311. Such a tower or pedestal can be expensive, more expensive than the turbine of the VAWT itself.
It is highly desirable to minimize the number, size, and/or expense of such supporting structures. According to a first aspect of the present invention, this is accomplished by providing a plurality of VAWTs clustered together, with common and less expensive supporting structures.
In more detail of this first aspect, there is provided a cluster of at least VAWTs. Each VAWT in the cluster has a structural support in common with at least one other VAWT of the cluster. Also, each VAWT is operatively connected to a separate useful driven mechanism, are electricity generating or fuel gas producing elements.
That is, there may be provided cluster of a plurality of widely spaced vertical axis wind turbines, each connected to a separate useful driven mechanism; and a plurality of structural supports for the VAWTs, including at least one structural support common to at least two of the plurality of VAWTs. Each VAWT may have a structural support in common with at least one other vertical axis wind turbine. Preferably, at least one of the VAWTs has an outrigger element operatively connected at or adjacent a top portion thereof and to an upper bearing; and the structural supports may comprise a strand (e. g. cable), rod, or bar operatively connected to the outrigger element. In fact each of the vertical axis wind turbines preferably has an outrigger element operatively connected at or adjacent a top portion thereof, and a structural support is operatively connected from each outrigger element to at least one other outrigger element. Also, preferably a strand is connected from at least one of the outrigger elements to a stationary support.
The cluster of vertical axis wind turbines preferably includes least three vertical axis wind turbines arranged on the imaginary periphery of a polygon, circle, or oval. Also, preferably at least one of the wind turbines rotates in the opposite direction to at least one other wind turbine. If an even number of wind turbines is provided then preferably alternating turbines along the imaginary periphery rotate in opposite directions.
While a wide variety of vertical axis wind turbines may be provided in the cluster, preferably they comprise three bladed Savonius wind turbines.
According to a second aspect of the invention, rather than clustering, a single VAWT is supported by a relatively light supporting structure, and an outrigger operatively connected to a stationary support.
That is, according to this second aspect, there is provided a vertical axis wind turbine comprising: A plurality of vanes, the vanes operatively connected to a central shaft structure mounted by at least one lower bearing for rotation about a substantially vertical axis. An outrigger operatively connected at or adjacent a top portion of the central shaft structure with an upper bearing operatively disposed between the outrigger and the central shaft structure. And a plurality of structural supports operatively connected to a plurality of different portions of the outrigger, and each also operatively connected to a stationary support.
The outrigger may comprise at least three distinct arms, and the structural supports may comprise at least three strands (such as steel cables), one operatively connected to each arm and to a different stationary support. Desirably, the lower bearing is mounted by a short tower or platform; for example the short tower or platform mounts the lower bearing about four-fourteen feet above the ground, and the bottoms of said vanes are above the lower bearing and positioned not to interfere with a human positioned under the bottoms of the vanes. Typically, a useful driven mechanism (e. g. electricity or fuel gas generator, pump, or the like) is operatively connected to the central shaft structure below the lower bearing and within the periphery of the short tower or platform. While the central shaft structure may comprise multiple shafts, preferably it comprises a single shaft that has a pivotal connection above the short tower or platform.
Again, while a wide variety of VAWTs may be utilized, preferably the vanes are at least partially curved, and the VAWT is a 2 or 3 bladed Savonius.
According to a third aspect of the invention, a Savonius or helical VAWT is provided that uses a central mounting structure which includes a hollow central shaft.
That is, according to this third aspect there is provided a Savonius or helical VAWT having a hollow central shaft, with a center pole extending through the shaft for mounting the Savonius or helical VAWT. And at least upper and lower bearings operatively disposed between the shaft and center pole for mounting the shaft for rotation with respect to the center pole about a substantially vertical axis. The bearings may be provided between the interior of the shaft and exterior of the center pole, and more than upper and lower bearings may be utilized, and the center pole and shaft may be tapered. Alternatively, the upper bearing is mounted exteriorly of the shaft and supported by a portion of the center pole above the shaft.
It is the primary object of the present invention to provide enhanced, yet less expensive and/or more easily fabricated or installed, mounting mechanisms for VAWTs. This and other objects of the invention will become clear from a detailed description of the invention, and from the appended claims.